Dark fiber switched bandwidth filter

Abstract

A device for affecting an individual bit rate limitation for each of a plurality of wavelength channels propagating in an optical fiber is disclosed. In a particular embodiment, the device comprises a directional coupler which is inserted into the optical fiber link. A recirculation path for a fraction of the power propagating in the fiber link extends between an output of the coupler and an input of the coupler. Illustratively, the recirculation path includes a wavelength division demultiplexer and an individual delay element for each wavelength channel. Optical switches may be utilized to block or permit passage of individual wavelength channels in the recirculation path.

What is claimed is: 
     
       1. A device for affecting an individual bit rate limitation for each of a plurality of wavelength channels propagating in an optical fiber link, said device comprising: a directional coupler inserted into said optical fiber link, and   a recirculation path extending between an output of said coupler and an input of said coupler, said coupler serving to direct a fraction of the power propagating in said optical fiber link to said recirculation path,   said recirculation path including a wavelength division multiplexing means for the purpose of separating said fraction of said power into said plurality of wavelength channels and a plurality of delay elements for delaying each of said wavelength channels in said recirculation path by an individual amount.   
     
     
       2. A device for affecting bit rate limitations for a plurality of individual wavelength channels propagating in an optical fiber link, said device comprising a directional coupler inserted into said optical fiber link,   a recirculation path extending between an output of said coupler and an input of said coupler, said coupler serving to direct a fraction of the power propagating in said optical fiber link to said recirculation path,   said recirculation path including wavelength division multiplexing means for the purpose of separating said fraction of said power into said plurality of wavelength channels, optical delay means, and switch means located between said demultiplexing means and said delay means for selectively transmitting selected ones of said channels to said delay means,   whereby wavelength channels transmitted by said switch means for bit rate limited and wavelength channels not transmitted by said switch means are not bit rate limited.   
     
     
       3. The device of claim 2 wherein said delay means comprises a single delay so that all bit rate wavelengths are limited by the same bit rate amount. 
     
     
       4. The device of claim 2 wherein said delay means comprises an individual delay means for each wavelength channel so that those bit rate wavelength channels are each limited by an individual bit rate amount. 
     
     
       5. A device for affecting bit rate limitations for a plurality of individual wavelength channels propagating in an optical fiber link, said device comprising a directional coupler inserted into said optical fiber link,   a recirculation path extending between an output of said coupler and an input of said coupler, said coupler serving to direct a fraction of the optical power propagating in said optical fiber link to said recirculation path,   said recirculation path including:   wavelength division multiplexing means connected to said output of said coupler,   a plurality of optical delay elements havingdifferent delay values, and   switch means for connecting individual wavelength channels outputted by said multiplexing means to different ones of said delay elements so that individual ones of said wavelength channels may be bit rate limited by different amounts.   
     
     
       6. A device for affecting an individual bit rate limitation for each of a plurality of individual wavelength channels propagating in an optical fiber lin, said device comprising first and second propagation paths,   means associated with said optical fiber link for dividing the optical power propagating in said fiber link between said first and second propagation paths,   means located in said second propagation path for separating optical radiation propagating in said second propagation path into said individual wavelength channels, and   a plurality of delay elements located in said second propagation path for providing each of said wavelength channels with an individual delay relative to said first propagation path, so that each of said individual wavelength channels is bit rate limited by a different amount.   
     
     
       7. The device of claim 6 wherein said dividing means is a directional coupler, said first propagation path extends straight through said directional coupler, and said second propagation path includes a recirculation path extending between an output of said coupler and an input of said coupler, said recirculation path including an individual delay element for each of said wavelength channels. 
     
     
       8. A device for affecting bit rate limitations for a plurality of wavelength channels propagating in an optical fiber link, said device comprising first and second propagation paths, said second propagation path providing a delay for optical power propagating therein relative to said first propagation path,   means associated with the optical fiber link for dividing the optical power propagating therein between the first and second propagation paths, and   optical switch means for selectively enabling particular ones of said wavelength channels to propagate in said second propagation path.   
     
     
       9. The device of claim 8 wherein said dividing means is a directional coupler, said first propagation path extends straight through said directional coupler, and said second propagation path includes a recirculation path extending between an output of said coupler and an input of said coupler, said recirculation path including means for providing said delay and switch means for directing optical power belonging to particular wavelength channels to said means for providing said delay. 
     
     
       10. The device of claim 8 wherein said second propagation path provides different delays for different ones of said wavelength channels.